The Third Generation Partnership Project (3GPP) involves collaboration between groups of telecommunications associations to create a globally applicable 3G mobile phone system specification. The 3GPP standards are based on Global System for Mobile Communications (GSM) specifications and encompass standards for radio, core network and service architecture.
There is currently work ongoing within 3GPP to introduce a new service called eCall. eCall is an automatically or manually initiated emergency voice call supplemented by a Minimum Set of Data (MSD) that includes vehicle specific and high accuracy location information. Using this information, the emergency services can accurately locate and provide more rapid assistance to accident victims, thus, saving more lives. As with the emergency voice call, the integrity of the MSD sent from the vehicle to the Public Safety Answering Point (PSAP) has to be ensured. It is expected that the MSD will be sent either during the emergency voice call set-up or immediately following the establishment of the emergency voice call.
It has been proposed to deliver the MSD component of the eCall using in-band modem signaling. This solution, however, has a number of drawbacks. One such drawback is that the use of in-band modem signaling prohibits any modifications to the user plane in the network and, therefore, may eliminate the MSD component when sent in-band. As the knowledge about the in-band transmission of the MSD is not available along the transmission path in the network, the use of in-band modem signaling requires that no future changes to the handling of the user plane in the network will be allowed.
Another drawback to using in-band modem signaling, involves the delay jitter experienced in a packet-based (e.g., Internet Protocol (IP)) network. This delay jitter, which is prevalent in modem in-band signaling over the packet-based network, will impact the reliability of the MSD delivery. A further drawback is that the large amount of redundancy employed in modem in-band signaling, which is used to ensure reliable delivery, results in a very long delivery time.